Use Activity Monitor to see whether a Mac app is using more of the CPU than it should.

When an app isn't responding or working correctly, it might use more of the processor (CPU) than it should, even when the app doesn't seem to be doing anything. As the CPU gets busier, it uses more energy, which reduces the time that your Mac can run on battery power. It also generates heat, which can cause the fans in your Mac to spin faster.

Use Activity Monitor to check CPU activity

Use the CPU pane of Activity Monitor to see how apps (processes) are affecting your CPU:

Open Activity Monitor, then choose View > All Processes.

Click the top of the “% CPU” column to sort by the percentage of CPU capability used by each process.

Apps normally use a larger percentage of the CPU when doing tasks that require intensive calculations, such as encoding video. But CPU use should decrease when the task is finished, and it should stop entirely when the app is no longer open. Any process except kernel_task that is consistently using more than 70 percent of your CPU is putting a significant load on the CPU and could be malfunctioning.

Quit any malfunctioning processes

To quit a process, first try quitting it normally. For example, quit Safari by switching to Safari and choosing Safari > Quit Safari.

If you can't quit a process normally, you can use Activity Monitor to force it to quit. Save any documents related to the process, then select the process in Activity Monitor and choose View > Quit Process.

If you don't recognize the name of a process, it might belong to macOS or another process that you do recognize. To see the relationships between processes, choose View > All Processes, Hierarchically. If you see that a process belongs to an app, such as Safari or Mail, quit the app before deciding whether to quit any of its processes.

To help avoid malfunctioning processes, keep your apps, plug-ins, and operating system up to date.

Information about products not manufactured by Apple, or independent websites not controlled or tested by Apple, is provided without recommendation or endorsement. Apple assumes no responsibility with regard to the selection, performance, or use of third-party websites or products. Apple makes no representations regarding third-party website accuracy or reliability. Risks are inherent in the use of the Internet. Contact the vendor for additional information. Other company and product names may be trademarks of their respective owners.